1. Field of the Invention
The present invention relates to a liquid crystal display (LCD) device, and more particularly to the electrode structure of a lateral electric field type LCD device.
2. Description of Related Arts
An LCD device controls the light transmittance by using the characteristic that liquid crystal (LC) molecules present different light polarization or refraction effects under different alignments so as to produce images. A twisted nematic (TN) LCD device has good light transmittance but an extremely narrow viewing angle as influenced by the structure and optical characteristic of the LC molecules.
To solve the transmittance and viewing angle problems, a twisted vertical alignment (TVA) model has been proposed so as to provide the high transmittance and the wide viewing angle. However, because the LC molecules are aligned in a vertical alignment manner, when the LC molecules are applied with a low voltage and the LCD device is watched at an inclined viewing angle, a gray-level inversion problem occurs, which causes the problem of color shift at an inclined viewing angle and influences a normal presentation of images of the LCD device.
Another approach to solving the problems is to use in-plane switching (IPS) technology in which inter-digital electrodes are formed on only one substrate to produce an electric field essentially parallel to the substrate. An IPS LCD device has the advantages of better image quality, improved viewing angle, and more brightness as compared to the TN LCD device.
In a conventional IPS LCD device, the two electrodes formed on one substrate are usually disposed in parallel with each other. The critical voltage required to drive the IPS LCD device is higher and the contrast is also worse. There is a strong need in developing new electrode structure to lower the critical voltage and improve the contrast of the LCD device.